Solid-state gas sensors are sensitive to the partial pressure (herein, “pressure”) or concentration of one or more gasses in a mixed atmosphere. Some types of solid-state gas sensors include those described in U.S. Pat. No. 5,279,795. These sensors are sensitive to one or more types of gas (for example, hydrogen (H2) and oxygen (O2)). Solid-state gas sensors are designed to provide measurements from which a gas pressure can be estimated. The sensors can also be employed to detect the rate of change in pressure, in order to infer the effects being monitored and measured.
For a given application, a gas sensing system can be designed to detect the pressure of a target gas (for example, H2). In addition to the target gas pressure, however, there are factors that can influence a gas sensor's measurements. For example, non-target gasses can influence the measurements. Additionally, other factors such as temperature and humidity can have an impact. Solid-state gas sensors can also have a delayed response to stimuli. For example, if there is a sudden target gas pressure change, the sensor might take from tenths to thousandths of seconds to reach near steady-state response at the new pressure.
Different approaches can be employed to mitigate the impact of these factors. For example, to reduce the effects of temperature, a heater can be employed to keep the sensor within a specified temperature range. Further, the gas sensing system can be calibrated over this temperature range to compensate for the effects of temperature. As another example, to reduce the impact of non-target gasses, a gas sensing system can be calibrated for a desired operating environment. For instance, the sensor response to the target gas (for example, H2) can be measured in air and the system calibrated accordingly. In such an example, an assumption can be made as to the pressure of non-target gasses and humidity. Humidity or water vapor, a gas, may be characteristic of common environmental conditions compared to other gasses, and may interfere with a target gas detection and measurement system and the gas sensing system could be calibrated according to this specific operating condition. As another example, to mitigate a delayed response of the sensor, a user can observe the direction of change in the sensor signal as an indicator of changes in target gas pressure, quasi-quantitatively, the direction of change being correlated with the developing phenomena.
The present gas sensing system can operate flexibly over a larger range of operating conditions by dynamically accounting for influencing factors.